Method for producing fatty acid alkyl ester composition

ABSTRACT

An object of the present invention is to solve a problem of separation and recovery of catalysts present in an alkali metal catalytic method currently often used, a problem of excess consumption of a catalyst by a free fatty acid in a raw material, and other problems, and to solve a problem of the presence of a large excess amount of alcohol in a conventional supercritical methanol method, and to provide a method for producing a fatty acid alkyl ester composition in a reaction system containing water and free fatty acid present. The present invention has attained the above-mentioned object by provided a method for producing a fatty acid alkyl ester composition using fats and oils containing a fatty acid glyceride and/or fatty acid, wherein alcohol and/or water is allowed to co-exist with the above-mentioned fats and oils and the reaction is conducted under conditions of a temperature of 100° C. to 370° C. and a pressure of 1 to 100 MPa.

TECHNICAL FIELD

The present invention relates to a method for producing fatty acid alkylester composition capable of being utilized effectively as a diesel fuel(particularly, bio-diesel fuel) by treating fats and oils containing afatty acid glyceride and/or fatty acid, more specifically, to a methodfor solving a problem of separation and recovery of catalysts present inan alkali metal catalytic method currently often used, a problem ofexcess consumption of a catalyst by a free fatty acid in a raw material,and a problem of solving a decrease in reactivity due to water in a rawmaterial and using a large excess amount of alcohol in a conventionalsupercritical methanol method, and producing a fatty acid alkyl estercomposition at high yield in a reaction system containing water and freefatty acid present.

BACKGROUND ART

It has been long known that a fatty acid alkyl ester is obtained bytransesterification of an alkyl alcohol with a mono-glyceride,di-glyceride and tri-glyceride (these are generically called fatty acidglyceride) which are main components of vegetable oils, animal fats andused fats and oils of them (for example, “Organic Chemistry Handbook,”Gihodo Publication, 1988, pp. 1407 to 1409). Furthermore, variousinvestigations have been made on a technology of producing a fatty acidalkyl ester which can be used as a diesel fuel from fats and oils,utilizing this reaction.

As a method for industrially producing a fatty ester from a fatty acidglyceride, there are long known methods in which a fatty acid glycerideis once hydrolyzed to be converted into a fatty acid, then, in thepresence of an acid catalyst or enzyme catalyst, the fatty acid isfurther subjected to a dehydration reaction (esterification reaction)with alcohols under an anhydrous condition to be converted into a fattyacid alkyl ester, however, these are scarcely used as an industrialproduction method due to low reaction rate. Currently, in industriallyoften used methods, a fatty tri-glyceride is subjected to atransesterification under an anhydrous condition in the presence of analkali metal catalyst under normal pressure at ambient temperature ortemperatures near the boiling point of an alcohol with shorter alkylchain. However, since, in this reaction, an alkali metal catalyst isdissolved in the reaction solution, there is a problem that the alkalimetal catalyst is dissolved in a solution of the product and separationand recovery thereof are difficult.

Further, waste oils and the like often contain water, consequently,removal of water in a raw material is inevitable as a pre-treatment, inuse of the above-mentioned alkali metal catalyst method. It is generalthat natural fats and oils contain a free fatty acid, and the content ofa free fatty acid differs depending on the origin of a raw material andits treatment method. For example, a waste edible oil contains 3% ormore of fatty acids and palm oil from an oil pressing process contains5% or more of fatty acids. When an alkali metal catalyst is used under acondition of inclusion of a large amount of free fatty acids, an alkalisoap becomes a by-product and an alkali metal catalyst in an excessamount is necessary, alternatively, there occurs a problem thatseparation of a fatty acid ester layer and a glycerin layer is difficultdue to a by-product alkali soap, and the like. Because of these reasons,when a transesterification of a fatty acid glyceride is conducted in thepresence of an alkali metal catalyst, a pre-treatment process isnecessary for removing a free fatty acid.

From the standpoint of avoiding such a problem, for example, JapanesePublished Unexamined Patent Application No. S61-14044 discloses also amethod of converting into an ester of a free fatty acid with the aid ofan acid catalyst, as a pre-treatment process. In this method, a freefatty acid is converted into an ester as a pre-treatment for conductinga transesterification of a fatty acid glyceride in the presence of analkali metal catalyst, however, there is a problem that removal of anacid catalyst is necessary before performing the nexttransesterification of a fatty acid glyceride and when an acid catalystremains, it is neutralized, consequently, the use amount of an alkalimetal catalyst increases corresponding to the neutralization amount.

As a method for producing a fatty ester not requiring theabove-mentioned pre-treatment process, there are also suggested methodsusing a solid acid catalyst (for example, Japanese Published UnexaminedPatent Application No. H6-313188). However, an acid catalyst has acritical defect that the reactivity thereof for a transesterification offats and oils is lower as compared with that of an alkali metalcatalyst, and there is a problem that a large amount of catalyst isnecessary in a transesterification using an acid catalyst.

On the other hand, there are recently also suggested so-calledsupercritical methanol methods in which a transesterification of fatsand oils is conducted under supercritical conditions for alcohol withoutusing a catalyst (for example, Japanese Published Unexamined PatentApplication No. 2000-204392, 2000-109883). However, in the supercriticalmethanol method, there is a disadvantage that a large excess amount ofalcohol should be present and higher temperatures of 300° C. or more arenecessary, for efficient progress of a transesterification. Further, inthis method, an effect of the presence of water in the reaction systemhas not been confirmed.

The present invention has been made notifying such conditions, and anobject thereof is to solve a problem of separation and recovery ofcatalysts present in an alkali metal catalytic method currently oftenused, a problem of excess consumption of a catalyst by a free fatty acidin a raw material, and a problem of decrease in transesterification dueto water in a raw material and to solve a problem of the presence of alarge excess amount of alcohol in a conventional supercritical methanolmethod, and the present invention provides a method for producing afatty acid alkyl ester, that is effective for conversion into a fattyacid alkyl ester from raw material oils which cannot be treated byconventional technologies such as a dark oil containing a free fattyacid as a main component discharged particularly from a purificationprocess in an oil production factory, and a waste edible oil having ahigh free fatty acid content and/or water content, and the like.

DISCLOSURE OF THE INVENTION

The present inventors have intensively studied and resultantly foundthat the above-mentioned problems can be solved by conducting a reactionunder specific conditions in the co-existence of alcohol and/or waterwith fats and oils, in producing a fatty acid alkyl ester compositionusing fats and oils containing a fatty acid glyceride and/or fatty acid.

The present invention has been made based on the above-mentionedfinding, and provides a method for producing a fatty acid alkyl estercomposition using fats and oils containing a fatty acid glyceride and/orfatty acid, wherein alcohol and/or water is allowed to co-exist with theabove-mentioned fats and oils and the reaction is conducted underconditions of a temperature of 100° C. to 370° C. and a pressure of 1 to100 MPa.

In this specification, “fats and oils” means those containing a fattyacid glyceride and/or fatty acid as described above and containing as amain component a generally called fatty acid mono-glyceride, fatty aciddi-glyceride or fatty acid tri-glyceride, and additionally, means afatty acid, and a mixture thereof. Namely, “fats and oils” also includewidely those containing no fatty acid glyceride and containing only afatty acid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing a difference in the relation between thereaction time and the yield of a methyl ester composition in anesterification reaction of a fatty acid and a transesterification of afatty acid glyceride by supercritical methanol treatment at 300° C. and30 Mpa.

FIG. 2 is a graph showing a difference in the relation between thereaction time of a transesterification of rapeseed oil by varioussupercritical alcohol treatments at 300° C. and the yield of theproduced various fatty acid alkyl ester compositions. The alcohols usedare methyl alcohol, ethyl alcohol, 1-propyl alcohol, 1-butyl alcohol and1-octyl alcohol.

FIG. 3 is a graph showing a difference in the relation between thereaction time of a transesterification of rapeseed oil by varioussupercritical alcohol treatments at 350° C. and the yield of theproduced various fatty acid alkyl ester compositions.

FIG. 4 provides graphs showing a difference in the relation between thereaction time of an esterification reaction of various fatty acids byvarious supercritical alcohol treatments at 300° C. and the yield of theproduced various fatty acid alkyl ester compositions.

FIG. 5 provides graphs showing a difference in the relation between thereaction time of a transesterification of rapeseed oil and anesterification reaction of various fatty acids by various supercriticalalcohol treatments at 300° C. and the yield of the produced variousfatty acid alkyl ester compositions.

FIG. 6 is a graph showing the relation between the pressure and theyield of a fatty acid alkyl ester composition at 300° C. under the samepressure for 20 minutes by a flow type apparatus.

BEST MODES FOR CARRYING OUT THE INVENTION

The method for producing a fatty acid alkyl ester composition of thepresent invention will be illustrated in detail based on its preferableembodiments.

The production method of the present invention is a method for producinga fatty acid alkyl ester composition using fats and oils containing afatty acid glyceride and/or fatty acid, wherein alcohol and/or water isallowed to co-exist with the above-mentioned fats and oils and thereaction is conducted under conditions of a temperature of 100° C. to370° C. and a pressure of 1 to 100 MPa.

Because of such a constitution, the method of the present invention doesnot cause a problem of separation and recovery of catalysts present inan alkali metal catalytic method, a problem of excess consumption of acatalyst by a free fatty acid in a raw material, and a problem of adecrease in transesterification due to water in a raw material, andfurther, solves a problem of the presence of a large excess amount ofalcohol in a conventional supercritical methanol method, and enablesproduction of a fatty acid alkyl ester composition at a high yield evenin the reaction system containing water and free fatty acid present.Further, the method of the present invention is effective for conversioninto a fatty acid alkyl ester from raw material oils which cannot betreated by conventional technologies such as a dark oil containing afree fatty acid as a main component discharged particularly from apurification process in an oil production factory, and a waste edibleoil having a high free fatty acid content and/or water content, and thelike.

In the production method of the present invention, the kind of reactionconducted and the number of steps of the reaction process are notparticularly restricted provided that alcohol and/or water is allowed toco-exist with the above-mentioned fats and oils and the reaction isconducted under conditions of a temperature of 100° C. to 370° C. and apressure of 1 to 100 MPa.

(First Embodiment)

The present invention preferably comprises a process in which alcoholand/or water is allowed to co-exist with the above-mentioned fats andoils containing at least a fatty acid glyceride, and the reaction isconducted under conditions of a temperature of 100 to 370° C. and apressure of 5 to 100 MPa (preferably 5 to 50 MPa), to convert a fattyacid glyceride and fatty acid contained in the above-mentioned fats andoils into a fatty acid alkyl ester (first embodiment). According to sucha first embodiment, water and alcohol, in particular water, works as anacid catalyst, a fatty acid glyceride reacts with alcohol by atransesterification, to give a fatty acid alkyl ester. A part of a fattyacid glyceride is hydrolyzed with water to give a fatty acid, however,since an esterification reaction progresses utilizing water and alcohol,particularly water as an acid catalyst to give a fatty acid alkyl ester,the co-existence of water with alcohol is useful.

In the first embodiment, to conduct the reaction under reactionconditions of, particularly, a temperature of 200 to 300° C. and apressure of 15 to 25 Mpa is suitable from the standpoint of energyconsumption amount and the corrosiveness of an apparatus. Namely, it isfurther preferable to comprise a process in which alcohol and/or wateris allowed to co-exist with the above-mentioned fats and oils containingat least a fatty acid glyceride, and the reaction is conducted underconditions of a temperature of 200 to 300° C. and a pressure of 15 to 25MPa, to convert a fatty acid glyceride and fatty acid contained in theabove-mentioned fats and oils into a fatty acid alkyl ester. Under thesereaction conditions, a fatty acid alkyl ester composition can beobtained particularly at high yield, and additionally, a fatty acidalkyl ester can be produced without using high temperature and highpressure conditions necessary in conventional supercritical methanolmethods. Therefore, the energy consumption amount is small,additionally, there is no problem with safety and the corrosiveness ofan apparatus, and there is no need to use an expensive special alloysuch as hastelloy, inconel and the like for avoiding corrosion of anapparatus by fluid of high temperature and high pressure.

This first embodiment comprises a process in which a fatty acidglyceride and fatty acid contained in the above-mentioned fats and oilsare converted into a fatty acid alkyl ester, and this process allows thereaction to be conducted in one step since it is inferred that byallowing alcohol and water to co-exist with raw material fats and oilscontaining at least a fatty acid glyceride, a fatty acid glyceridecauses a hydrolysis reaction and/or transesterification and a fatty acidcontained in fats and oils and/or a fatty acid produced by theabove-mentioned hydrolysis reaction is converted into a fatty acid alkylester by an esterification reaction. In these reactions, alcohol andwater, particular water, works as an acid catalyst under the conditionsof reaction temperature and reaction pressure according to the presentinvention.

(Second Embodiment)

In the present invention, it is also preferable to comprise a firstprocess of allowing water to co-exist with the above-mentioned fats andoils containing at least a fatty acid glyceride and conducting thereaction under conditions of a temperature of 100 to 370° C. and apressure of 1 to 100 MPa, to convert the fatty acid glyceride containedin the above-mentioned fats and oils into a fatty acid, and a secondprocess of adding alcohol to the product from the above-mentioned firstprocess and further conducting the reaction under conditions of atemperature of 100 to 370° C. and a pressure of 5 to 100 MPa, to convertthe fatty acid contained in the product from the first process into afatty acid alkyl ester (second embodiment). Such a second embodiment isuseful particularly since an unreacted fatty mono-glyceride, fattydi-glyceride and fatty tri-glyceride scarcely remain and are convertedinto a fatty acid in the first process and converted into a fatty acidalkyl ester effectively in the second process.

In the second embodiment, to conduct the reaction under reactionconditions of, particularly, a temperature of 150 to 300° C. and apressure of 15 to 25 Mpa is suitable from the standpoint of the energyconsumption amount and the corrosiveness of an apparatus. Namely, it isfurther preferable to comprise a first process of allowing water toco-exist with the above-mentioned fats and oils containing at least afatty acid glyceride and conducting the reaction under conditions of atemperature of 150 to 300° C. and a pressure of 5 to 25 MPa, to convertthe fatty acid glyceride contained in the above-mentioned fats and oilsinto a fatty acid, and a second process of adding alcohol to the productfrom the above-mentioned first process and further conducting thereaction under conditions of a temperature of 200 to 300° C. and apressure of 15 to 25 MPa, to convert the fatty acid contained in theproduct from the first process into a fatty acid alkyl ester. Thesereaction conditions are particularly useful because of the same reasonas in the case under the above-mentioned suitable reaction conditions inthe first embodiment, namely, since a fatty acid alkyl ester compositioncan be obtained particularly at a high yield and additionally, thereoccurs no problem of high temperature and high pressure conditionsnecessary in conventional supercritical methanol methods.

In this second embodiment, the reaction is conducted in two stepscomprising a first process of converting a fatty acid glyceridecontained in the above-mentioned fats and oils and a second process ofconverting a fatty acid contained in the product from the first processinto a fatty acid alkyl ester. Of them, the first process converts afatty acid glyceride into a fatty acid by a hydrolysis reaction shown bythe following reaction formula:

(wherein, n represents 1, 2 or 3, and R represents a saturated orunsaturated hydrocarbon group.).

As shown in the above-mentioned reaction formula, in the first process,a fatty acid glyceride in fats and oils used as a raw material isreacted with water, to produce a fatty acid (R^(n)COOH) liberated fromthe glyceride. This free fatty acid is subjected to the second processdescribed later.

The above-mentioned reaction formula shows a fatty acid glyceride as anexample, and additionally, when a fatty di-glyceride and/or fattymono-glyceride are contained in fats and oils as a raw material, theyare also hydrolyzed in the same manner.

In the second process, the free fatty acid produced in the hydrolysisreaction in the first process is, or, when a fatty acid is containedfrom the first in fats and oils as a raw material, this fatty acid andthe above-mentioned free fatty acid are reacted with alcohol, to producea fatty acid alkyl ester by an esterification reaction.

In the second process, esterification is conducted by thus reacting afatty acid and alcohol. It has been clarified by the present inventorsthat the reaction speed of this esterification reaction is larger thanthe transesterification of conversion into a fatty ester by a reactionof a fatty acid glyceride and alcohol (see, FIG. 1). FIG. 1 is a graphshowing a difference in the relation between the reaction time and theyield when an esterification reaction and transesterification areconducted at 300° C. and 30 Mpa.

Here, unreacted substances in the transesterification include mainlypartial transesterified substances such as mono-glycerides and the like.This partial transesterified substance leads to an increase in the totalglycerol amount causing an engine trouble when utilized in engine fueloil. Therefore, it is inevitable to effect complete conversion into afatty acid alkyl ester, however, a large amount of energy (longerreaction time) is necessary for this.

In the second embodiment of the present invention, it is particularlypreferable that the first process is conducted at a temperature of 150to 300° C., particularly 250 to 300° C. and a pressure of 5 to 25 MPa,particularly 15 to 25 MPa for 15 to 25 minutes, and the second processis conducted also at a temperature of 250 to 300° C. and a pressure of15 to 25 MPa for 15 to 25 minutes.

(Third Embodiment)

The present invention also preferably comprises a process of allowingalcohol to co-exist with the above-mentioned fats and oils containing nofatty acid glyceride and conducting the reaction under conditions of atemperature of 100 to 370° C. and a pressure of 5 to 100 MPa(preferably, 5 to 50 MPa), to convert the fatty acid contained in theabove-mentioned fats and oils into a fatty acid alkyl ester (thirdembodiment). Such a third embodiment is useful particularly since afatty acid can be easily converted into a fatty acid alkyl ester whichis impossible in an alkali metal catalytic method.

In the third embodiment, the reaction is suitably conducted at atemperature of 200 to 300° C. and a pressure of 15 to 25 Mpa. Namely, itis further preferable to comprise a process of allowing alcohol toco-exist with the above-mentioned fats and oils containing no fatty acidglyceride and conducting the reaction under conditions of a temperatureof 200 to 300° C. and a pressure of 15 to 25 MPa, to convert the fattyacid contained in the above-mentioned fats and oils into a fatty acidalkyl ester. These reaction conditions are particularly useful becauseof the same reason as in the case under the above-mentioned suitablereaction conditions in the first embodiment, namely, since a fatty acidalkyl ester composition can be obtained particularly at high yield andadditionally, there occurs no problem of high temperature and highpressure conditions necessary in conventional supercritical methanolmethods.

This third embodiment comprises a process in which the above-mentionedfats and oils containing no fatty acid glyceride are used and the fattyacid contained in the fats and oils is converted into a fatty acid alkylester, and this is a simple process method since a fatty acid alkylester composition can be obtained only via the second process(esterification reaction) and without the first process (hydrolysisreaction) in the above-mentioned second embodiment.

In the production method of the present invention, when theabove-mentioned fats and oils contain a fatty acid glyceride, it ispreferable to use water in an amount of 3 to 1000 mol, particularly 30to 400 mol per mol of the fatty acid glyceride from the standpoint ofeffectively progressing a hydrolysis reaction for conversion into afatty acid, and it is preferable to use alcohol in an amount of 3 to1000 mol, particularly 30 to 400 mol per mol of the fatty acid glyceridefrom the standpoint of effectively converting the fatty acid glycerideinto a fatty acid alkyl ester directly by a transesterification,further, effectively converting the fatty acid produced by theabove-mentioned hydrolysis reaction into a fatty acid alkyl ester.

When the above-mentioned fats and oils contain a fatty acid, it ispreferable to use alcohol in an amount of 1 to 330 mol, particularly 10to 130 mol per mol of the fatty acid from the standpoint of effectivelyconverting the fatty acid into a fatty acid alkyl ester by anesterification reaction.

In the production method of the present invention, the reaction time isnot particularly restricted provided the reaction is conducted withinthe above-mentioned range of the reaction temperature and reactionpressure, and the reaction time is appropriately set corresponding tothe conditions of the reaction temperature and reaction pressure. In oneexample, when the reaction temperature is 250 to 300° C. and thereaction pressure is 15 to 30 MPa, for example, the reaction time ispreferably 4 to 60 minutes, further preferably 30 to 50 minutes.

The raw material fats and oils used in the production method of thepresent invention include vegetable oils, animal oils and used wasteoils thereof, and the like. The vegetable oils include natural vegetablefats and oils such as coconut oil, palm oil, palm kernel oil, soybeanoil, rapeseed oil and the like. The animal oils include natural animalfats and oils such as beef tallow, lard, fish oil and the like. Thewaste oils include waste oils obtained after use of these vegetable oilsand animal oils for a specific object. These fats and oils can be usedsingly or in admixture.

As the alcohol used in the production method of the present invention,alcohols having 1 to 10 carbon atoms are useful. It is preferable touse, particularly, lower alcohols having about 1 to 5 carbon atoms suchas methyl alcohol, ethyl alcohol, propyl alcohol, i-propyl alcohol,butyl alcohol, 2-butyl alcohol, i-butyl alcohol, t-butyl alcohol, pentylalcohol and the like, from the standpoint of producing a lower alkylester excellent as a diesel fuel oil, particularly, a bio-diesel fueloil. Of them, particularly methyl alcohol is preferable since the costthereof is low and recovery thereof is easy. Of course, higher alcoholshaving 6 or more carbon atoms such as decyl alcohol can also be used.

As the reaction apparatus used in the production method of the presentinvention, any apparatus can be used provided it can stand a highpressure and high temperature. When a hydrolysis reaction is conductedwithout a catalyst, alcohol and/or water works as an acid catalyst underthe conditions according to the present invention.

The fatty acid alkyl ester composition obtained by the production methodof the present invention can be used in various applications, and isparticularly useful as a diesel fuel, among others, as a bio-dieselfuel.

The present invention will be illustrated further in detail by examplesand comparative examples below. However, the scope of the invention isnot at all limited to these examples.

EXAMPLE 1 Example According to the Second Embodiment of the PresentInvention (First Case)

<1> First Process (Hydrolysis Reaction of Fatty Acid Glyceride)

1 ml of rapeseed oil (tri-glyceride content: 97.5%, free fatty acidcontent: 2.5%) and 4 ml of water (tri-glyceride/water=1/217 mol ratio)were filled in an Inconel-625 reaction tube having a content volume of 5ml. This reaction tube was placed into a tin bath controlled at apredetermined temperature and reacted while shaking under apredetermined pressure for a predetermined time. After the predeterminedreaction time, the reaction tube was quickly removed from the tin bath,and placed in a water bath and cooled quickly to room temperature. Thecontent of the reaction tube was transferred into a measuring cylinder,and allowed to stand still for 30 minutes, to give two layers of anupper layer composed of the produced fatty acid (in some cases,containing an unreacted fatty acid glyceride) and a lower layer composedof water containing a glycerol. The upper layer was removed from this,and evaporated to completely remove water present in a trace amount.

<2> Second Process (Methyl-Esterification Reaction)

Next, into a reaction tube was added the fatty acid (in some cases,containing an unreacted fatty acid glyceride) obtained in the firstprocess and about 4 ml of methanol (raw material tri-glyceride/methanolratio=1/100 mol) to give a total amount of 5 ml, and amethyl-esterification reaction was conducted at a predeterminedtemperature under a predetermined pressure for a predetermined time.After predetermined reaction time, the reaction tube was cooled quicklyto room temperature, and unreacted methanol and the produced water wereremoved from the content of the reaction tube. The resulting product wasdissolved in fresh methanol, and the composition thereof was analyzedusing a refractive index detector by high performance liquidchromatography (HPLC). From the composition analysis result, the yieldof a methyl ester was obtained.

Conditions of the hydrolysis reactions in the examples (Examples 1-1 to1-13) are shown in Table 1, and conditions of the methyl-esterificationreaction are shown in Table 2, and the yields of fatty methyl estersobtained in the examples are shown together in Table 2.

TABLE 1 (Conditions of first process/hydrolysis reaction) ReactionRapeseed Water Temperature Pressure time Example oil (ml) (ml) (° C.)(Mpa) (min) Example 1.0 4.0 255 20 20 1-1 Example 1.0 4.0 255 20 25 1-2Example 1.0 4.0 255 20 30 1-3 Example 1.0 4.0 270 35 15 1-4 Example 1.04.0 270 35 20 1-5 Example 1.0 4.0 270 35 25 1-6 Example 1.0 4.0 270 3530 1-7 Example 1.0 4.0 300 60 6 1-8 Example 1.0 4.0 300 60 8 1-9 Example1.0 4.0 300 60 12 1-10 Example 1.0 4.0 350 90 1 1-11 Example 1.0 4.0 35090 2 1-12 Example 1.0 4.0 350 90 3 1-13

TABLE 2 (Conditions of second process/methyl-esterification reaction andyield of methyl ester) Reaction Methanol Temperature Pressure timeYield* Example (ml) (° C.) (Mpa) (min) (%) Example 4.0 255 19 20 78 1-1Example 4.0 255 19 25 93 1-2 Example 4.0 255 19 30 98 1-3 Example 4.0270 25 15 89 1-4 Example 4.0 270 25 20 98 1-5 Example 4.0 270 25 25 981-6 Example 4.0 270 25 30 98 1-7 Example 4.0 300 30 6 81 1-8 Example 4.0300 30 8 90 1-9 Example 4.0 300 30 12 96 1-10 Example 4.0 350 43 2 601-11 Example 4.0 350 43 3 82 1-12 Example 4.0 350 43 4 97 1-13 *Yield:this shows a proportion against the theoretical value of amethyl-esterified compound when converted to 100% (also in the followingexamples)

EXAMPLE 2 Example According to the Second Embodiment of the PresentInvention (Second Case)

<1> First Process (Hydrolysis Reaction of Fatty Acid Glyceride)

A hydrolysis reaction of a fatty acid glyceride was conducted accordingto the same operation procedure as in Example 1, excepting that thevolume ratio of rapeseed oil (tri-glyceride content: 97.5%, free fattyacid content: 2.5%) and water was changed while keeping the reactiontemperature and reaction time constant.

<2> Second Process (Methyl-Esterification Reaction)

Next, a methyl-esterification reaction was conducted according to thesame operation procedure as in Example 1 excepting that a predeterminedreaction temperature, reaction pressure and reaction time were applied.

The composition of the reaction product was analyzed by the sameprocedure as in Example 1, and from the analyzed result, the yield of amethyl ester was obtained.

Conditions of the hydrolysis reactions in the examples (Examples 2-1 to2-6) are shown in Table 3, and conditions of the methyl-esterificationreaction are shown in Table 4, and the yields of fatty methyl estersobtained in the examples are shown together in Table 4.

TABLE 3 (Conditions of first process/hydrolysis reaction) ReactionRapeseed Water Temperature Pressure time Example oil (ml) (ml) (° C.)(Mpa) (min) Example 0.62 4.38 255 18 30 2-1 Example 1.0 4.0 255 19 302-2 Example 4.0 1.0 255 35 30 2-3 Example 0.62 4.38 270 30 20 2-4Example 1.0 4.0 270 35 20 2-5 Example 4.0 1.0 270 60 20 2-6

TABLE 4 (Conditions of second process/methyl-esterification reaction andyield of methyl ester) Reaction Methanol Temperature Pressure time YieldExample (ml) (° C.) (Mpa) (min) (%) Example 4.38 255 19 30 95 2-1Example 4.0 255 19 30 94 2-2 Example 1.0 255 19 30 63 2-3 Example 4.38270 25 20 98 2-4 Example 4.0 270 25 20 96 2-5 Example 1.0 270 25 20 612-6

EXAMPLE 3 Example According to the Third Embodiment of the PresentInvention

(Esterification Reaction of Fatty Acid)

An esterification reaction of a fatty acid and methanol was conductedusing, as a raw material, palmitic acid, stearic acid, oleic acid,linoleic acid and linolenic acid (all manufactured by Nacalai Tesque)commercially available as a reagent, and under conditions of volumeratio, temperature, pressure and reaction time shown in Table 5. For theesterification reaction of a fatty acid and methanol, a fatty acid andmethanol were filled at a mole ratio of 1:42 in a Inconel-625 reactiontube having a content volume of 5 ml, and the same procedure as in themethyl-esterification reaction in Example 1 was conducted. After removalof unreacted methanol and produced water in the same manner as inExample 1, the reaction product was dissolved in fresh methanol and HPLCanalysis was conducted. From the HPLC analysis result, the conversionfrom a fatty acid into a fatty acid alkyl ester (=yield of methyl ester)was obtained. The results are shown in Table 5 together with reactionconditions.

TABLE 5 Reac- Tem- tion Fatty Fatty acid (ml)/ perature Pressure timeYield Example acid methanol (ml) (° C.) (Mpa) (min) (%) Example 3-1C_(16–0) 0.91:4.09 270 17 20 90 Example 3-2 C_(16–0) 0.91:4.09 300 24 788 Example 3-3 C_(16–0) 0.91:4.09 350 43 4 75 Comparative C_(16–0)0.91:4.09 400 75 2 92 example 3-1 Example 3-4 C_(18–0) 0.91:4.09 270 1720 98 Example 3-5 C_(18–0) 0.91:4.09 300 24 7 98 Example 3-6 C_(18–0)0.91:4.09 350 43 4 100 Comparative C_(18–0) 0.91:4.09 400 75 2 100example 3-2 Example 3-7 C_(18–1) 0.91:4.09 270 17 20 98 Example 3-8C_(18–1) 0.91:4.09 300 24 7 98 Example 3-9 C_(18–1) 0.91:4.09 350 43 498 Comparative C_(18–1) 0.91:4.09 400 75 2 94 example 3-3 Example 3-10C_(18–2) 0.91:4.09 270 17 20 98 Example 3-11 C_(18–2) 0.91:4.09 300 24 798 Example 3-12 C_(18–2) 0.91:4.09 350 43 4 87 Comparative C_(18–2)0.91:4.09 400 75 2 80 example 3-4 Example 3-13 C_(18–3) 0.91:4.09 270 1720 99 Example 3-14 C_(18–3) 0.91:4.09 300 24 7 96 Example 3-15 C_(18–3)0.91:4.09 350 43 4 93 Comparative C_(18–3) 0.91:4.09 400 75 2 61 example3-5 C_(16–0): palmitic acid, C_(18–0): stearic acid, C_(18–1): oleicacid, C_(18–2): linoleic acid, C_(18–3): linolenic acid

EXAMPLE 4 Example According to the First Embodiment of the PresentInvention

(Hydrolysis of Tri-Glyceride and Esterification of Fatty Acid: 1-StepReaction)

Reaction of Fats and Oils Containing a Free Fatty Acid andTri-Glyceride, and Water and Methanol

1.6 ml of rapeseed oil (tri-glyceride content: 97.5%, free fatty acidcontent: 2.5%), a predetermined amount of water and predetermined amountof methanol were filled in an Inconel-625 reaction tube having a contentvolume of 5 ml. This reaction tube was placed into a tin bath controlledat predetermined temperature and reacted while shaking under apredetermined pressure for 4 minutes. After the reaction, the reactiontube was quickly removed from the tin bath, and placed in a water bathand cooled quickly to room temperature. Unreacted methanol and water andby-product of glycerin were removed from the content of the reactionproduct. The composition of the resulting product was analyzed in thesame manner as in Example 1, and from the composition analysis result,the yield of a methyl ester was obtained.

Reaction conditions in examples (Examples 4-1 to 4-8) are shown in Table6, and the yields of fatty methyl esters obtained in the examples areshown together in Table 6.

TABLE 6 Reaction Fat and Water Methanol Temper- Pressure time YieldExample oil (ml) (ml) (ml) ature (° C.) (Mpa) (min) (%) Example 4-1 1.60.05 3.35 350 43 4 98 Example 4-2 1.6 0.1 3.3 350 43 4 97 Example 4-31.6 0.2 3.2 350 45 4 98 Example 4-4 1.6 0.3 3.1 350 46 4 98 Example 4-51.6 0.4 3.0 350 46 4 97 Example 4-6 1.6 0.5 2.9 350 48 4 95 Example 4-71.6 0.8 2.6 350 50 4 95 Example 4-8 1.6 1.6 1.8 350 50 4 94 Example 4-91.6 0.05 3.35 300 26 10 91 Example 1.6 0.1 3.3 300 27 10 91 4-10 Example1.6 0.5 2.9 300 27 10 92 4-11 Example 1.6 0.8 2.6 300 28 10 92 4-12Example 1.6 1.6 1.8 300 28 10 92 4-13 Example 1.6 0.8 2.6 270 18 40 944-14 Example 1.6 1.6 1.8 270 19 40 94 4-15

The fatty acid alkyl ester composition obtained in each example ofExamples 1 to 4 could be confirmed to be useful as a bio-diesel fueloil.

EXAMPLE 5 Esterification Reaction and Transesterification of Fatty Acid

An esterification reaction of a fatty acid and alcohol or atransesterification of rapeseed oil and alcohol was conducted using, asa raw material, fats and oils and alcohols shown in Table 7, underconditions of mole ratio, temperature, pressure and reaction time shownin Table 7. Since about 98.5% of rapeseed oil is composed of atri-glyceride, the reaction from rapeseed oil can be judged to be atransesterification.

The reaction product was subjected to HPLC analysis in the same manneras in Example 1, from the HPLC analysis result, conversion into a fattyacid alkyl ester from a fatty acid or rapeseed oil (=yield of alkylester) was obtained. The results are shown in Table 7 together with thereaction conditions.

TABLE 7 Alcohol/fats and oils Temperature Pressure Reaction Example(mole ratio) Fats and oils Alcohol (° C.) (Mpa) time (min) Yield (%)Example 42/1 C_(18–3) Methanol 300 20 8 96.2 5-1 Example 42/1 C_(18–2)300 20 8 95.1 5-2 Example 42/1 C_(18–1) 300 20 8 95.8 5-3 Example 42/1C_(18–0) 300 20 8 94.7 5-4 Example 42/1 C_(16–0) 300 20 8 94.0 5-5Example 42/1 Rapeseed 300 20 15 98.0 5-6 oil Example 42/1 Rapeseed 35043 4 98.0 5-7 oil Example 42/1 C_(18–3) Ethanol 300 15 12 94.6 5-8Example 42/1 C_(18–2) 300 15 14 97.4 5-9 Example 42/1 C_(18–1) 300 15 1495.9 5-10 Example 42/1 C_(18–0) 300 15 15 91.2 5-11 Example 42/1C_(16–0) 300 15 14 91.7 5-12 Example 42/1 Rapeseed 300 15 45 96.7 5-13oil Example 42/1 Rapeseed 350 25 10 97.1 5-14 oil Example 42/1 C_(18–3)1-propanol 300 10 15 97.0 5-15 Example 42/1 C_(18–2) 300 10 14 92.7 5-16Example 42/1 C_(18–1) 300 10 14 92.3 5-17 Example 42/1 C_(18–0) 300 1014 89.6 5-18 Example 42/1 C_(16–0) 300 10 14 90.1 5-19 Example 42/1Rapeseed 300 10 45 96.1 5-20 oil Example 42/1 Rapeseed 350 23 14 98.85-21 oil Example 42/1 C_(18–3) 1-butonal 300 9 15 97.3 5-22 Example 42/1C_(18–2) 300 9 14 92.4 5-23 Example 42/1 C_(18–1) 300 9 14 86.1 5-24Example 42/1 C_(18–0) 300 9 14 82.5 5-25 Example 42/1 C_(16–0) 300 9 1481.1 5-26 Example 42/1 Rapeseed 300 9 45 87.1 5-27 oil Example 42/1Rapeseed 350 23 14 95.3 5-28 oil Example 42/1 Rapeseed 1-octanol 300 645 68.7 5-29 oil Example 42/1 Rapeseed 350 19 20 90.7 5-30 oil C_(16–0):palmitic acid, C_(18–0): stearic acid, C_(18–1): oleic acid, C_(18–2):linoleic acid, C_(18–3): linolenic acid

From the results shown in Table 7, the following matters are evident.

In the transesterification using rapeseed oil as a raw material of fatsand oils (reaction temperature: 300° C.), the treatment time is 15minutes and the yield is about 98% in a reaction with methanol, on theother hand the treatment time is 45 minutes and the yield is about 87%in a reaction with butanol. Further, it is found, in thistransesterification, that when the number of carbon atoms in alcoholdecreases, its reactivity increases (see FIG. 2, for the above-mentionedmatters). Even in the same transesterification at a reaction temperatureof 350° C., the same matter is applied (see, FIG. 3). In this example, abatch type apparatus was used, however, it is also possible to use aflow type apparatus which shows no influence of pressure, namely, whichcan effect treatment under the same pressure condition (describedlater). For reference, the critical temperature and critical pressure ofvarious alcohols used in the examples are shown in Table 8 together withthe temperature and pressure conditions in the examples.

TABLE 8 Critical Critical Pressure in example temperature pressure (MPa)Alcohol (° C.) (Mpa) 300° C. 350° C. Methanol 239 8.09 20 43 Ethanol 2436.38 15 25 1-propanol 264 5.06 10 23 1-butanol 287 4.90 9 23 1-octanol385 2.86 6 19

As shown in Table 8, when a batch type apparatus is used and if thenumber of carbon atoms of alcohol is higher, pressure in the reactiontube decreases, and resultantly, there is a possibility of a decreasealso in the yield of a fatty acid alkyl ester. On the other hand, when areaction is conducted using a flow type apparatus under the samecondition, results shown in a graph of FIG. 6 are obtained. That is, itbecomes evident that even if compared under the same pressure condition,if the number of carbon atoms of alcohol is higher, yield alsodecreases, and a conclusion is obtained that a flow type apparatus givesthe same result as that of a batch type apparatus.

Esterification reactions when various fatty acids are used as a rawmaterial of fats and oils show little difference in reactivity dependingon the kind of alcohol and fatty acid, and the reactions are completedin a treatment time of about 15 minutes (see, FIG. 4).

From the above-mentioned results, it is clear that a method by anesterification reaction has higher reactivity as compared with a methodby a transesterification.

Since the condition of reaction pressure varies between variousalcohols, a mutual comparison of them is difficult, however, thereaction of each alcohol is conducted under the conditions of the samepressure and the same temperature By this, it is clear that a reaction(esterification reaction) using various fatty acids as a raw material offats and oils gives faster alkyl-esterification as compared with areaction (transesterification) using rapeseed oil (see FIG. 5).

Therefore, a reaction can be completed in a shorter time, namely, energycan be saved, when a tri-glyceride is hydrolyzed to give a fatty acid,then, the fatty acid is alky-esterified.

The fatty acid alkyl ester composition obtained in each example ofExample 5 can be confirmed to be useful as a bio-diesel fuel oil.

Industrial Applicability

The present invention can solve a problem of separation and recovery ofcatalysts present in an alkali metal catalytic method, a problem ofexcess consumption of a catalyst by a free fatty acid in a raw material,and a problem of a decrease in transesterification due to water in a rawmaterial, and further, solves a problem of the presence of a largeexcess amount of alcohol in a conventional supercritical methanolmethod, and can produce a fatty acid alkyl ester composition withoutbeing influenced in the progress of a reaction even water and free fattyacid contained in the reaction system.

1. A method for producing a fatty acid alkyl ester composition usingfates and oils containing a fatty acid glyceride and/or fatty acid,wherein alcohol and/or water is present along with said fats and oils ina same reaction vessel and the reaction is conducted under conditions ofa temperature of 100° C. to 370° C. and a pressure of 1 to 100 MPa,wherein the amount of water is 3 to 1000 mol per mol of the fatty acidglyceride contained in said fats and oils, and the amount of alcohol is1 to 330 mol per mol of the fatty acid contained in said fats and oils.2. The method for producing a fatty acid alkyl ester compositionaccording to claim 1, wherein alcohol and water is present in said samereaction vessel along with said fats and oils, and said fats and oilscontain a fatty acid glyceride, and conducting the reaction underconditions of a temperature of 100° C. to 370° C. and a pressure of 5 to100 MPa, to convert the fatty acid glyceride and fatty acid contained insaid fats and oils into a fatty alkyl ester.
 3. The method for producinga fatty acid alkyl ester composition according to claim 1, comprising afirst step wherein water is present along with said fats and oilscontaining at least a fatty acid glyceride in said same reaction vesseland said reaction is conducted under conditions of a temperature of 100°C. to 370° C. and a pressure of 1 to 100 MPa, to convert the fatty acidglyceride contained in said fats and oils into fatty acid, and a secondstep wherein alcohol is added to the product from said first step and areaction is conducted under conditions of a temperature of 100° C. to370° C. and a pressure of to 100 MPa, to convert the fatty acidcontained in the product from the process into a fatty acid alkyl ester.4. The method for producing a fatty acid alkyl ester compositionaccording to claim 1, comprising a process wherein alcohol is presentwith said fats and oils in said vessel and said fats and oils contain nofatty acid glyceride and conducting the reaction under conditions of atemperature of 100° C. to 370° C. and a pressure to 5 to 100 MPa, toconvert the fatty acid contained in said fats and oils into a fatty acidalkyl ester.
 5. The method for producing a fatty acid alkyl estercomposition according to claim 1, wherein the amount of water is 30 to400 mol and the amount of alcohol is 30 to 400 mol per mol of the fattyacid glyceride contained in said fats and oils, and the amount ofalcohol is 10 to 130 mol per mol of the fatty acid contained in saidfats and oils.
 6. The method for producing a fatty acid alkyl estercomposition according to claim 1, using alcohol having 1 to 10 carbonatoms as said alcohol.
 7. The method for producing a fatty acid alkylester composition according claim 1, wherein said fatty acid alkyl estercomposition is used as a diesel fuel oil.
 8. The method for producing afatty acid alkyl ester composition according to claim 1, wherein saidreaction is conducted in the absence of a metal alkali catalyst and anacid catalyst.
 9. The method for producing a fatty acid alkyl estercomposition according to claim 1, wherein said reaction is conducted inthe absence of any catalyst.